The present application relates to interconnect structures, and more particularly to interconnect structures with enhanced electromigration performance.
Metal interconnects are used to interconnect semiconductor devices into circuits. As circuits are scaled to smaller dimensions in a continual effort to provide increased density and performance, the interconnect linewidth becomes increasingly narrow, which in turn renders metal interconnects more susceptible to deleterious effects such as electromigration. Electromigration occurs when a high density of current flows through a metal interconnect, which in turn causes metal atoms to migrate toward the anode end of the metal interconnect. Over an extended period of time, the accumulation of metal at the anode end of the metal interconnect significantly increases the local mechanical stress in the system, causing an increase in resistance or failure of the metal interconnect, both of which reduce reliability of the circuits. Therefore, there remains a need to enhance electromigration performance of metal interconnects when relative current densities through metal interconnects continue to increase as the linewidths of metal interconnects shrink.